Suppression of mutations in mitochondrial DNA by tRNAs imported from the cytoplasm

Mitochondrial import of a cytoplasmic transfer RNA (tRNA) in yeast requires the preprotein import machinery and cytosolic factors. We investigated whe ther the tRNA import pathway can be used to correct respirator,, deficienci es due to mutations in the mitochondrial DNA and whether this system can be transferred into human cells. We show that cytoplasmic tRNAs with altered aminoacylation identity can be specifically targeted to the mitochondria an d participate in mitochondrial translation. We also show that human mitocho ndria, which do not normally import tRNAs, are able to internalize yeast tR NA derivatives in vitro and that this import requires an essential yeast im port factor.